Untitled

Oxygen Activation Chemistry of Pacman and Hangman Porphyrin Architectures Based on Xanthene and Dibenzofuran Spacers

“…3. Trends in bond lengths and angles of macrocyclic core structures and side chains agree well with those observed in related systems including H 4 (DPA), H 4 (DPB), and 1,2-bis [5-(2,3,7,8-12,13,17,18-octaethylporphyrinato)]-cis-ethene porphyrins (80)(81)(82)(83).…”

Oligoporphyrins with One-and Two-Atom Covalent Bridges: Synthesis and Reactivity, Solid-State, Solution and Electronic Structures, Spectroscopy and Applications

“…More evidence was added to this picture by including the (E )-and (Z )-Zn/H 2 and -Zn 2 derivatives, using semi-empirical PM3 calculations using HyperChem. 49 Again, the P and U conformers of the (E) isomers were found as local minima close in energy. 156 The lower-symmetry dimer 112 was included so that N-H tautomeric forms could be examined, as there were ambiguities in the previous studies of 25a due to the presence of tautomers and poor agreement with vibrational spectroscopic data.…”

“…Indeed, the authors were able to form the (E) isomers quantitatively by irradiation for one hour in tetrahydrofuran (THF) solution with a 750 W incandescent lamp. 49 As in the voltammetry experiments of Arnold and coworkers, these conversions could be followed easily due to the remarkable differences between the electronic spectra of the stereoisomers (Section IV.A).…”

“…49,158 Shishporenok and Chirvony reported that a complicating factor was the unavoidable presence of the corresponding (E) isomers, either as endogenous impurities that accumulated upon storage, or as the products of photoisomerization. The latter reaction was confirmed by illumination with an incandescent lamp.…”

“…The ultrafast deactivation of the photoexcited (Z ) isomers recalls the discussion above on the excited-state conformations of the (E) isomers. 49,158 With the availability of β-unsubstituted DAP/TriAP and the interest in NLO possibilities of conjugated diporphyrins, instead of the more crowded OAP type, Anderson and coworkers prepared the Zn 2 dimer 42a and recorded its emission and excited-state properties. 66 The steady-state fluorescence was dominated by the NIR maximum at 765 nm [steady-state fluorescence quantum yield (Φ F ) 0.041, S 1 lifetime 0.76 ns].…”